OBJECTIVE: Development of selective inhibitors of oncorna virus reverse transcription; emphasis on anthracycline drugs and analysis of their drug-receptor interactions. APPROACH: New anthracycline drugs have been synthesized and their QSAR analyzed for specificity as inhibitors of DNA-directed RNA polymerase vs. RNA-directed DNA polymerase. Drugs with high specificity for the latter have been studied in vivo in an RSV-chick system, or oncorna virus-induced murine leukemia.